Precision reed drawing-in apparatus and method

ABSTRACT

A reed drawing-in apparatus provides a method whereby a warp thread can be properly and smoothly drawn in a respective gap between adjoining dents of even an extremely high-density reed without being cut off during the reed drawing-in operation. A threader apparatus which can stand longer use is also used. The work carrier sequentially stops at a respective gap between adjoining dents of the reed while it moves towards the latitudinal direction of said reed. A gap opener carried on the work carrier temporarily enlarges a target gap and a threader thrusts in the enlarged gap so as to hook a warp thread sorted out from a thread supply section. Thread is drawn into the reed which is provided with a hook part thereon.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a method of drawing a warp thread in alooms reed. This reed drawing-in apparatus and method allows a warpthread to be properly and smoothly drawn Into a respective gap betweenadjacent dents of a reed where the dents are laid with extremely highdensity. Threads are not cut off during the reed drawing-in operation. Athreader has a greater useful life. This invention serves to streamlinereed drawing-in especially for the production of high-density fabrics.

2. Prior Art

Recently, for use as a plotting scale for manufacturing electronicparts, much attention has been drawn to a plain fabric which is woven byaccurately intercrossing weft and warp threads of extremely thin statuswith precisely equal interval between adjacent threads. However, inorder to weave this type of fabric, a high-density reed must be used.The number of dents in some extreme cases reaches 400 dents/inch. Thedents are finely and densely disposed. With the prior reed drawing-inapparatus, it was impossible to draw a warp thread into such ahigh-density reed as mentioned above. Thus, warp threading into such ahigh-density reed depended on manual labor by an experienced andskillful worker.

An apparatus has been proposed in Japanese Patent Application Laid-OpenNo- 61-502472 wherein a gap between adjacent dents is probed byprojecting light on the reed surface so as to analyze light which hasgot through an interval between adjacent reed-dents and a warp thread ismechanically drawn into said gap. However, with such a prior apparatusas mentioned above, it can probe said gap well, but the problem ofsmoothly drawing an extremely thin warp thread into said gap withoutdoing damage on said warp thread remains unsolved so that it is stillfar from industrial applicability.

On the other hand, the present applicant has proposed a high-precisionreed drawing-in apparatus in Japanese Patent Publication No.8-16301which comprises a search light source irradiating search light onto areed, a CCD camera picturing the reed surface irradiated with the searchlight, a microcomputer for calculating the distance to a target gapbetween adjacent dents on the basis of a picture signal output from saidCCD camera and for outputting a numerical movement command signal inproportion to the calculated distance, and a threader having a hook partwhich is formed thinner than the gap between adjacent dents of the reed,wherein the hook part is thrust into the gap so as to hook a warp threadand draw it into said gap, and a work carrier for carrying said searchlight source, CCD camera, microcomputer and threader which sequentiallymoves from one gap to another on the reed in accordance with saidnumerical movement command signal so as to draw a warp thread into atarget gap with the hook part of the threader. With this apparatus,because of the precisely associated movement between the accuratelymoving work carrier and the thin hook part of the threader in reeddrawing-in operation, it has become possible to properly draw a warpthread even into a high-density reed with 300 dents/inch.

However, even with the high-precision reed drawing-in apparatus asmentioned above, as the density of dents becomes higher, such as 400dents/inch, the hook part of the threader must be thinner and thinner.Therefore, the tip end of the hook part trembles under the influence ofvibration and so on. This causes drawing-in errors of the warp thread orbreakup of the hook part so that the operation needs to be frequentlysuspended and a number of broken hook parts must be replaced.

DISCLOSURE OF THE INVENTION

The above-mentioned problems encountered in the reed drawing-inapparatus described in Japanese Patent Publication No.8-16301 andproposed by the present applicant are solved by this invention. Thepresent invention provides a reed drawing-in method whereby a warpthread can be properly and smoothly drawn into a respective gap betweenadjacent dents of even an extremely high-density reed without being cutoff during the reed drawing-in operation. The operation is rarelysuspended and a high-precision apparatus is used in this method.

The method adopted in the present invention is characterized in that awarp thread, held in a thread supply section arranged opposite to thereed of a loom, is sequentially drawn into a respective gap by means ofthe association between a "Gap Opening Operation" where the dentsdisposed on both sides of the respective gap are temporarily andsequentially enlarged by intermittently stopping a work carrier providedwith a gap opener and a threader while the work carrier is moving in thelatitudinal direction of the reed, and a "Threader Inserting Operation"where the threader is thrust into the enlarged gap.

The apparatus adopted in the present invention is characterized in thatthe associated movement between a gap opener which temporarily spreadsapart the dents disposed on both sides of a target gap just locatedwhere a work carrier has stopped, and a threader which is thrust intothe gap enlarged by the gap opener and hooks a warp thread from thethread supply section and draws said warp thread into the enlarged gap,is incorporated into the work carrier which sequentially stops inresponse to the respective gap while moving in the latitudinal directionof the reed.

Now, further comments on the constitution of the present invention aregiven as follows. First, a work carrier movement is adopted in thepresent invention for sequentially spreading apart the dents disposed onboth sides of a respective gap. This work carrier is under the numericalcontrol of an input movement command signal and sequentially andprecisely stops in response to the respective gap while moving in thelatitudinal direction of the reed.

The precise shift of the work carrier across the reed is realized bymeans of a light beam source, a CCD camera and a microcomputer carriedon the carrier. Namely, when the light beam projects a localised searchbeam towards the surface of the reed where a number of dents aredisposed, a CCD camera converts the quantity of light received, whichvaries according to whether there is a dent at a searched area, intophotoelectricity and outputs said light quantity as a picture signal toa microcomputer. Then, a microcomputer calculates the distance to atarget gap existing between adjacent dents on the basis of said picturesignal output from said CCD camera and then outputs a numerical movementcommand signal so as to numerically control a shift motor installed inthe work carrier and shift said work carrier to a computed position.

Then, the gap opener and the threader are also carried on the workcarrier of the present invention. The gap opener is a mechanical partwhich is thrust into a respective target gap between adjacent dents ofthe reed just opposite where the work carrier has stopped under thenumerical control of the input movement command signal as mentionedabove and temporarily enlarges the gap. As a gap opener, a sharp-pointedor lanceolate pin by means of a back-and-forth driving mechanism (e.g. aservomotor and cam mechanism) can be adopted. In this case, the tip endof the pin aims at a gap corresponding to the position where the workcarrier has stopped. Turning to the threader, it is thrust into theenlarged gap and hooks a warp thread from the thread supply sectionarranged opposite the reed with a hook part provided at its tip end soas to draw said warp thread into the reed. The threader moves inassociation with and subsequently to the gap opener also by means of aback-and-forth driving mechanism such as a servomotor. Therefore, thehook part is longitudinally arranged on the threader along a gap formedby the reed-dents. However, there is no problem even if the threadermoves successively following the motion of the gap opener when the workcarrier has stopped. In this connection, it is preferable that theinstant the work carrier has stopped at a fixed position under thenumerical control of the input movement command signal, the computerreceiving the information that the work carrier has stopped successivelysends a thrust signal and a reed drawing-in signal to the drivingmechanism of the gap opener and the threader respectively. The reeddrawing-in apparatus embodied in the present invention is based on therelationship between the "Gap Opening Operation" where the gap openertemporarily enlarges a respective gap by separating reed-dents disposedon both sides of the gap and the "Threader Inserting Operation" wherethe threader is thrust into the enlarged gap. Therefore, even when thereed drawing-in operation is performed on a high-density reed having anextremely fine gap between adjacent reed-dents, there is no case wherethe warp thread is damaged or cut off due to excessive stress such asfriction during operation.

The reed drawing-in apparatus embodied in the present invention canautomatically perform a fast reed drawing-in operation even on ahigh-density reed with more than 400 dents/inch. Therefore, it is animprovement over the prior art disclosed in Japanese Patent PublicationNo.8-16301. This invention streamlined preparatory work in a factorywhere a high-density fabric is manufactured. Its industrialapplicability is extremely high.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of the reed drawing-in apparatusembodied in the present invention;

FIG. 2 is a schematic sectional view of the work carrier carrying a CCDcamera, a beam source, a gap opener and a threader;

FIG. 3 is a fragmentary enlarged sectional view of the work carriershowing the motions of a gap opener and a threader embodied in thepresent invention;

FIG. 4 is an enlarged perspective view of a warp thread suctiontensioner excluding the beam source of FIG. 1;

FIG. 5 is a fragmentary enlarged view of a warp thread selector of thework carrier showing said selector hooking a warp thread sorted out froma warp thread holder and drawing said thread toward the deliveryposition;

FIG. 6 is a fragmentary enlarged view of a warp thread cutter and a warpthread manipulator of the work carrier showing said cutter cutting off awarp thread and the manipulator picking up the cut-off thread;

FIG. 7 is a block diagram showing the three-way control signal flowbetween a microcomputer, a CCD camera and a servomotor embodied in thepresent invention;

FIG. 8 is a perspective view of the gap opener and the threader embodiedin the present invention seen from the underside of the reed showing thestate thereof immediately before the sharp-pointed pin of the gap openerprojects through the reed:

FIG. 9 is a perspective view of the gap opener and the threader embodiedin the present invention seen from the underside of the reed showing thestate thereof where the sharp-pointed pin of the gap opener is thrustinto a target gap of the reed so as to enlarge said gap and the threaderstarts to move towards the enlarged gap;

FIG. 10 is a perspective view of the gap opener and the threaderembodied in the present invention seen from the underside of the reedshowing the state thereof where the threader has been thrust into thetarget gap enlarged by the sharp-pointed pin;

FIG. 11 is a bird's-eye view of the gap opener and the threader embodiedin the present invention showing the state thereof where the hook partof the threader has extended upwardly a little above the reed;

FIG. 12 is a graphical representation showing the waveform of thepicture signal output from the CCD camera in accordance with theintensity of search light irradiated from the beam source before thesmoothing of said picture signal;

FIG. 13 is a graphical representation showing the smoothed waveform ofthe picture signal of FIG. 12;

FIG. 14 is an explanatory view showing the position of a warp threadmanipulator immediately before a warp thread picked up by saidmanipulator is delivered to the threader;

FIG. 15 is an explanatory view showing the state where the warp threadmanipulator has rotated so as to carry the warp thread to the deliveryposition for handing it over to the threader and has released it;

FIG. 16 is an explanatory view showing the state where the end portionof the warp thread released by the manipulator has been taken into thewarp thread suction tensioner;

FIG. 17 is a partially perspective view showing the warp threadarrangement mechanism adopted in the reed drawing-in apparatus embodiedin the present invention;

FIG. 18 is a partially perspective view showing the state where thebracket of the warp thread arrangement mechanism has reached a lowermostposition;

FIG. 19 is a schematic view showing the moving state of the workcarrier; and

FIG. 20 is a flow chart showing the main steps of the reed drawing-inoperation embodied in the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The whole movement of a reed drawing-in apparatus (D) embodied in thepresent invention and shown in the accompanying drawings is achievedsubstantially as follows.

First, as shown in FIG. 1, a high-density reed (400 dents/inch) (R) ishorizontally placed on the apparatus (D). With this apparatus (D), areversably rotatable ball screw (B) driven by a shift control motor(servomotor) (M) is horizontally suspended below said reed (R). Saidball screw (B) engages with a work carrier (WC) so as to make saidcarrier shift just by a required distance. In reference to theaccompanying drawings, a beam source (11), a CCD camera (12), a gapopener (21) and its back-and-forth driving mechanism or servomotor (22)as well as a threader (23) and its back-and-forth driving mechanism orservomotor (24) for causing thrust and draw-in movements respectivelyare shown in FIG. 2. A warp thread suction tensioner (31) is shown inFIG. 4 while a warp thread manipulator (32), a warp thread cutter (33),a warp thread transport hook (34) and a warp thread selector (35)respectively are shown in FIGS. 5 and 6. A warp thread arrangementmechanism (40) is shown in FIGS. 17 and 18, the above technical featuresbeing all systematically carried on the work carrier (WC) along thetransfer passage of the warp thread.

Further commenting on the above-mentioned embodiment in accordance withthe accompanying drawings, FIG. 2 shows that said beam source (11) andwarp thread suction tensioner (31) are placed above the reed (R) whichis arranged on the reed drawing-in apparatus (D), while said CCD camera(12) and threader (23) are opposedly placed below the reed (R) againstthe beam source (11). Said beam source (11), warp thread suctiontensioner (31), CCD camera (12) and threader (23) are all arranged sothat they shift together with the work carrier (WC). Accordingly, a gapbetween adjacent dents of the high-density reed (R) is searched by thebeam source (11), and is picturized in the CCD camera (12). Thepicturized gap is analyzed with a microcomputer (C) installed on thework carrier (WC). Then, the analysis data is sent to the servomotor (M)as shown in FIG. 7 so that the work carrier (WC) shifts accordingly andreaches a gap between adjacent dents where the search light intensitybecomes largest directly below the gap. Then, when the work carrier (WC)is stopped at said gap, said computer (C) emits a thrust signal to theservomotor (22) of the gap opener (21) so as to actuate upwardprojection of a sharp-pointed pin (21a)(a gap opener tip) through thetarget gap. The projection of the sharp-pointed pin (21a) causes thedents on both sides of the gap to separate so that the gap becomesenlarged. Then, after the enlargement of the gap, said computer (C)emits a threading signal to the servomotor (24) of the threader (23).The actuation of the threader (23),causes its hook part (2f) to bethrust into the gap and to project a little above the reed (R) (seeFIGS. 10 and 11). Then, a warp thread (W) is led into the upper side ofthe reed (R) and the end portion of the thread (W) is drawn into thewarp thread suction tensioner (31). This warp thread suction tensioner(31) takes in the warp thread (W) through its suction opening (31a)under a required air suction pressure produced by a compressor (notshown in the drawings). The warp thread (W) taken into the tensioner(31) is arranged 50 that it meets the hook part (2f) projecting abovethe reed (R). This way, when the warp thread (W) is hooked on the nookpart (2f), the threader (23) retreats below the reed (R) by means of theservomotor (24) so that the warp thread (w) is drawn into the gapbetween adjacent dents of the reed (R).

Hereinafter, the concrete constitution realizing the above mentionedmotions of a reed drawing-in apparatus embodied in the present inventionis described in more detail.

A infrared LED (light emitting diode) of super-high luminance is adoptedas the beam source (11) provided above the reed (R) arranged on the reeddrawing-in apparatus (D) embodied in the present invention. This LED isrotatable upward and escapably installed on a bracket (H) hinged withthe work carrier (WC). When the reed (R) is arranged on the reeddrawing-in apparatus (D), the LED along with a warp thread suctiontensioner (31) are spring biased upward so that they can move to aposition where they do not interfere with the reed (R).

Then, the CCD camera (12) is arranged below the reed (R) for the purposeof linear image processing. Charge coupled elements are arranged in oneline parallel with the latitudinal direction of the reed-dents (4096picture elements:2μ/picture element). This camera (12) excitesphotoelectrical conversion according to the intensity of search lightpassing the interval between adjacent dents of the reed (R) so as tooutput a picture signal. The picture signal output by this camera (12)is sent to the microcomputer (C) for smoothing as shown in FIGS. 12 and13. Then, as shown in FIG. 13. an address (1900) where the quantity orlight received has peaked is read as a target gap. With the reeddrawing-in apparatus embodied in the present invention, the computer (C)is preliminarily programmed so that it can read the current position ofthe sharp-pointed pin (21a) of the gap opener (21) and that of the hookpart (2f) of the threader (28). Therefore, the computer (C)automatically emits a movement command signal to the work carrier (WC)so as to shift the sharp-pointed pin (21a) and the hook part immediatelybelow an adjacent gap on the right-hand side of the previously threadedgap.

The shift of the sharp-pointed pin (21a) and the hook part (2f) to thelatitudinal direction of the reed-dents (across the dents) or the shiftthereof to the subsequent gap accompanies that of the work carrier (WC).The carrier (WC) shifts by rotation of the ball screw (B) provided atthe lower portion of the reed drawing-in apparatus (D). Thus, rotating aservomotor (M) engaged with the ball screw (B) at a fixed rate (see acontrol mechanism chart in FIG. 7) enables the sharp-pointed pin (21a)and the hook part (2f) to accurately shift to the target gap.

And when the ball screw (B) in response to the movement command signaloutput by the computer (C) shifts the work carrier (WC) to apredetermined position or when the sharp-pointed pin (21a) and the hookpart (2f) reaches a location directly below a target gap or at theintermediate position between adjacent dents, the microcomputer (C)emits a thrust signal to a servomotor (22) of the gap opener (21) so asto cause the sharp-pointed pin (a gap opener tip)(21a) to project abovethe reed (R). Because the tip of the pin (21a) is aimed at the targetgap, it is properly thrust into an intermediate position betweenadjacent dents without colliding with the dents and enlarges the gap.Subsequently, said microcomputer (C) sends a threading signal to theservomotor (24) of the threader (23) so as to actuate said servomotor(24). Because the target gap is already enlarged by the sharp-pointedpin (21a) of the gap opener (21), after the actuation of the servomotor(24), the hook part (2f) smoothly projects through the gap and extendsupwardly a little above the reed (R) (see FIG. 10). The sharp-pointedpin (21a) of the gap opener (21) provided with the reed drawing-inapparatus embodied In the present Invention has a tapered tip, thediameter of which at the foot is 2 mm and the length of which along thesloping side is 7 mm. Because the hook part (2f) of the threader (23)adopted in the reed drawing-in apparatus embodied in the presentinvention has a tip portion, the thinnest part of which is 3 μ and thethickest part of which is only 70 μ and the gap is enlarged by 2 mm withthe sharp-pointed pin (21a) as mentioned above, and also because thehook part (2f) is accurately carried and positioned just below anintermediate position between adjacent dents, it can be smoothly andspaciously inserted into a reed even with 400 dents/inch as shown inFIG.10.

Then, when the hook part (2f) has reached its topmost position, theoperation by means of each mechanism as described below for hooking awarp thread on the hook part (2f) begins.

First, as shown in FIG. 1, one warp thread (W) is selected from a numberof the files of warp threads (W·W . . . ) orderly arranged in a warpthread holder (51) of the reed drawing-in apparatus (D) by means of theshedding motion of a pair of leasing strings that are not shown in thedrawings. The warp thread selector (35) carried on the central part ofthe work carrier (WC) catches this selected warp thread (W) (see FIG.5). Namely, a hook (25a) capable of catching only one warp thread (W) isformed on said warp thread selector (35). When the selected thread ishooked on the hook (35a), the hook (35a) swings towards the work carrier(WC) so as to draw the selected warp thread (W) near a fixed position.

Then, when the selected warp thread (W) hooked on the hook (35a) hasshifted to the fixed position towards the work carrier (WC), the warpthread transport hook (34) provided on the selector (35) starts moving.This hook (34) is a warp thread relay mechanism whereby the selectedthread (W) hooked on the selector (35) is shifted to a position wherethe warp thread manipulator (32) can pick up the warp thread (W), andconsists of a hook member horizontally moving to and from as shown inFIGS. 5 and 6. In this way, the selected warp thread (W) transported bythe warp thread transport hook (34) is delivered to the manipulator(32).

The warp thread manipulator (32) has a pair of forks (32a) and (32b)between which the warp thread (W) transported from the selector (35) isput. Then, the warp thread (N) between said forks (32a) and (32b) is cutat a fixed location with scissor blades (3e) and (3e) of the warp threadcutter (33) (see FIG. 6) and the manipulator (32) revolves around asupport axis (32c) in the direction of the arrow indicated in FIG. 14with the warp thread (W) between the forks (32a) and (32b) so as tocarry the warp thread (W) to the delivery position (see FIG. 15).

The warp thread (W) picked up and carried to the delivery position bythe manipulator (32) with its forks (32a) and (32b), as shown in FIG.15, is taken into the warp thread suction tensioner (31) by air suctionpressure so that it can be held stable while being hooked on the hookpart (2f) of the threader (21) After the completion of the delivery, asshown in FIG. 16, the manipulator (32) further proceeds to revolvearound the support axis (32c) and returns to the original position Then,the end portion of the warp thread (W) hooked on the book part (2f) isfurther taken into the suction tensioner (31) so that it is held tautand straight. Because the suction opening (31a) of the warp threadsuction tensioner (31) is formed flatly compressed in the direction ofthe hook part (2f) and also has a deep-cut slit (31b) formed in thedirection of the forks (32a) and (32b) of the manipulator (32) which hasarrived at the delivery position, even if the warp thread (w) is partlyslack when the forks (32a) and (32b) have picked up and carried it, itsend portion is taken in and pulled into the suction opening (31a) sothat it is held taut and stable.

After the completion of a series of associated motions of each mechanismsuch as the above-mentioned warp thread selector (35), warp threadcutter (33) and warp thread transport hook (34) at the thread supplysection of the reed drawing-in apparatus embodied in the presentinvention for the purpose of sorting out a warp thread from the files ofwarp threads (W·W . . . ) and supplying it to the delivery position, thethreading signal output by the microcomputer (C) switches the servomotor(24) of the threader (23) to the return mode. Then, while the warpthread (W) hooked on the hook part (2f) is still held sufficiently taut,it slips out of the suction opening (31a) against air suction pressureof the warp thread suction tensioner (31), is threaded through the gapand is discharged from the hook part (2f) below the reed (R). Then,after the hook part (2f) has been retracted downwardly from the enlargedgap of the reed-dents, the servomotor (22) of the gap opener (21) isalso switched to the return mode so that the sharp-pointed pin (21a) isretracted downwardly from the enlarged gap of the reed-dents. Uponretraction of the sharp-pointed pin (21a), the reed-dents elasticallyrecover.

It should be noted that the same warp thread arrangement mechanism isadopted in the present invention as disclosed in Japanese PatentPublication No.8-16301 "A reed drawing-in apparatus of looms" proposedby the present applicant. Namely, a warp thread arrangement mechanism(40) wherein a cut-off warp thread is orderly arranged, is providedbelow the reed (R) so that a warp thread drawn into the reed-dents givesno trouble either to the search for a target gap or to the operation ofthe gap opener (21) and the threader (23) respectively.

This warp thread arrangement mechanism (40) is now explained more indetail with reference to FIGS. 17 and 18.

When a newly selected warp thread (W) is drawn into a gap of thereed-dents, a warp thread receiving bracket (42) for bundling warpthreads (W) lowers according to the rotational angle of a cam (43).Then, a swing arm (41) moving horizontally to and from by means of aboss (44a) of a crank plate (44) rotates above the bracket (42) andbrushes aside a newly drawn-in warp thread (W) from the underside of thereed (R). The bracket (42) turns to rise so that it raises a bundle ofwarp threads including the warp thread (W) which has been newly drawn-inand put aside, and then the swing arm (41) returns to the originalposition passing under the bracket (42).

Following the warp thread arrangement as mentioned above, themicrocomputer (C) calculates the distance between the gap where thepreviously drawn-in warp thread (W) is and an adjacent or target gap tothe right-hand side of said previously drawn-in gap so as to command thework carrier (WC) to shift to said target gap. In this way, sequentiallydrawing warp threads (W) into the reed-dents enables successive reeddrawing-in operations. Another point to be emphasized regarding theembodiment of the present invention is that in order to securely hook awarp thread onto the warp thread selector (35) from the warp threadholder (51), two sensors (52) and (53) are provided on the selector (35)in the direction of the files of warp threads (W·W . . . ) as shown inFIG. 1 and are arranged so that a headmost warp thread (N) approachesthe sensor (52) farther from the selector (35)

This point is explained more in detail as follows. The warp threadbolder (51) for orderly holding the files of warp threads (W·W . . . )slides to and from against the selector (35) by means of a rack andpinion which is not shown in the drawings. The selector (35) carried onthe work Carrier (NC) also slides towards the files of warp threads (W)arranged in the holder (51) during the reed drawing-in operation inresponse to the driving of the servomotor (M). In this case, when thedensity of the files of warp threads (W) is low and the headmost warpthread (W) is away from a position where it can be detected with thesensor (52) because the selector (35) slides too little, the holder(51)is slid towards the selector (35) by moving said rack and pinion onepitch at a time. On the contrary, when the density of the files of warpthreads is high and the headmost warp thread (W) has reached a positionwhere it can be detected with the sensor (53) because the selector (35)slides too much, the holder (51) including the files of warp threads isretracted by means of said rack and pinion.

As a result of repeated experiments with the reed drawing-in apparatusembodied in the present invention, it has been confirmed that saidapparatus can cope with even a high-density reed (R) with 400 dents/inchwithout interrupting the reed drawing-in operation at all.

Finally, a series of reed drawing-in operations is chronologicallyexplained as follows in reference to FIGS. 19 and 20. First, themicrocomputer (C) installed on the work carrier (WC) confirms byanalyzing a picture signal output by the CCD camera that the workcarrier (WC) is set on a predetermined starting point (O) of the bellscrew (R) (step "a" of FIG. 20). Then, the work carrier (NC) is shiftedfrom the starting point (O) to a reed drawing-in initial point (S) ofthe reed (R) (step "b" of FIG. 20). This initial point (S) is located ata gap in one of the two marginal regions between low-density areas (RL)formed at both sides of the reed (R) and a high-density area (RH)interposed between said low-density areas (RL) while the ultimate point(E) is located at a gap in the other marginal region.

Then, the microcomputer (C) installed on the work carrier (NC) analyzesand detects the position of the first gap and shifts the work carrier(WC) just below said gap under the numerical control and stops it (step"c" of FIG. 20). When the sharp-pointed pin (21a) of the gap opener (21)projects through the target gap where the work carrier (WC) has stopped,the dents disposed on both sides of the gap are separate so that saidgap is enlarged (step "d" of FIG. 20). The hook part (2f) of thethreader (23) is thrust into the enlarged gap so that it projects alittle above the reed (R) (step "e" of FIG. 20). One warp thread (W) isselected from the files of warp threads (W·W . . . ) (step "f" of FIG.20) and this selected thread is subject to air suction pressure whilebeing hooked on the hook part (2f) of the threader (23) (step "g" ofFIG. 20). Thereafter, the warp thread (W) is drawn into the gap of thereed-dents by retracting the threader (23) below the reed (R) (step "h"of FIG. 20). After the sharp-pointed pin (21a) of the gap opener (21)has been retreated below the reed (R) (step "i" of FIG. 20) and the warpthread (W) hooked on the hook part (2f) has been unhooked (step "j" ofFIG. 20), one cycle of reed drawing-in operation is completed (step "k"of FIG. 20).

Then, the microcomputer (C) reads whether there is a gap left or not andif so, the same reed drawing-in operation as mentioned above isperformed on an adjacent gap (see "N" route in step "k" of FIG. 20).

Otherwise or when the work carrier (WC) has shifted to the ultimatepoint (E) of the reed (R), all the reed drawing-in operations are overand the work carrier (WC) is retracted to the starting point (O) (see"Y" route in step "k" of FIG. 20). In this regard, whether there is anygap left is read in accordance with the change of waveforms of picturesignals output by the CCD camera (refer to FIG. 13). In short, saidwaveforms vary in accordance with the change of the reed-dents densityin the two marginal regions between the high-density area (RH) and thelow-density areas (RL). Although reed drawing-in operation is performedon all the reed-dents in the high-density area (RH) in the presentembodiment, it is also possible to perform said operation bypreliminarily programming a given interval between one gap and the nextgap in the microcomputer (C).

The embodiment of the present invention to be disclosed herein issubstantially as described above. However, it should be understood thatthe present invention is not limited to said embodiment, but can bemodified in various ways within the scope of the accompanying claims.

For example, two servomotors (22) and (24) are adopted as back-and-forthdriving control mechanism for the sharp-pointed pin (21a) of the gapopener (21) and the threader (23) respectively in the presentembodiment, but it is also possible to drive them with just oneservomotor by causing time lag between the movement of the sharp-pointedpin (21a) and that of the hook part (2f) of the threader (23). It isalso possible to adopt a driving mechanism by means of fluid pressuresuch as an air cylinder instead of those two servomotors.

The sharp-pointed or lanceolate pin (21a) which is thicker at the footis adopted as a tip of the gap opener (21) in the present embodiment,but it is also possible to insert an oar-like slat into a gap ofadjacent reed-dents and twist said slat in the gap so as to enlarge it.

It should be understood that the above-mentioned modifications are onlya few examples of modified embodiments in accordance with the working ofthe present invention, and those modifications are obviously within thetechnical scope of the present invention.

We claim:
 1. A method of drawing a warp thread into a gap betweenadjacent reed-dents in a high-density reed of a loom, comprising thesteps of:(a) locally irradiating a surface of the reed with an infraredsearch beam; (b) converting a quantity of light of said search beamwhich varies according to whether there is a dent at the irradiatedsurface into photoelectricity using a CCD camera to obtain a picturesignal output having a waveform; (c) determining a peak location of thepicture signal by smoothing said signal; (d) calculating a distance to atarget gap between adjacent dents on the basis of the peak locatingusing a microcomputer, the peak location corresponding to said targetgap; (e) inputting a calculated value of the distance to said target gapas a numerical movement command signal into a work carrier movablelatitudinally of the reed so as to precisely shift said work carrier toa reed drawing-in position, said work carrier being provided with a gapopener having a sharp-pointed pin with a thicker underpart for enlargingsaid gap and with a threader for drawing a warp thread into the gap; (f)gradually separating the dents disposed on opposite sides of the targetgap by thrusting said pin into said gap so as to enlarge the target gap;(g) thrusting the threader into the enlarged gap and hooking a warpthread from a thread supply section arranged opposite the reed, thereby,drawing said warp thread into the gap.
 2. A reed drawing-in apparatusfor a high-density reed of a loom, comprising a work carrier movable inthe latitudinal direction of the reed to a reed drawing-in positionunder a numerical movement command signal, said work carriercarrying:(a) an infrared beam source for locally irradiating a surfaceof the reed with an infrared beam; (b) a CCD camera arranged to converta quantity of light of said beam varying according to whether there is adent at the irradiated surface into photoelectricity so as to obtain apicture signal output having a waveform; (c) a microcomputer arranged tocalculate distance to a target gap between adjacent dents on the basisof a peak location determined from a smoothed waveform derived from saidpicture signal output and to output said numerical movement commandsignal so as to precisely shift said work carrier to a reed drawing-inposition; (d) a gap opener having a sharp-pointed pin with a thickerunderpart which is arranged to separate the dents on opposite sides ofthe target gap in such a manner that a tip of said gap opener is firstthrust into said gap so as to gradually enlarge the gap when the carrierhas reached the reed drawing-in position; (e) a threader arranged tothrust into a gap enlarged by the sharp-pointed pin of said gap openerfor hooking a warp thread from a thread supply section arranged oppositethe reed and for drawing the warp thread into the gap.
 3. A reeddrawing-in apparatus as claimed in claim 2, wherein the sharp-pointedpin of the gap opener and the threader are aligned in the longitudinaldirection of the gap between said adjacent dents.